Rajwinder Kaur2017-02-232017-02-232012http://krishikosh.egranth.ac.in/handle/1/5810002276The present study was conducted to study carbon sequestration and its distribution in different soil organic carbon pools and to study soil aggregation and organic carbon storage in different sized aggregates under different land use systems in sub-montaneous districts of Punjab. Two sites selected for the study were Takarla and Mukerian and four land-use systems were selected viz. cropland, forestry, agro-forestry and grassland. Soil pH varied from slightly alkaline to moderate alkaline at Takarla while at Mukerian, soil pH was slightly alkaline. At both sites, pH was higher in grassland and EC was higher in cropland. Forest soils had higher silt and clay content at Takarla, while grassland possessed higher clay content at Mukerian. Bulk density at both sites was higher in cropland. Available N was higher in forestry (234.78 kg ha-1) at Takarla while in Mukerian, it was higher in grassland (199.70 kg ha-1). At both sites, cropland possessed highest available P and K. At Takarla, CEC was higher in cropland (10.83 Cmol kg-1) and in Mukerian, it was highest in forestry (12.65 Cmol kg-1). In surface soils at both sites, the water-stable macro-aggregates (WSA>2mm) were highest in grassland soils while the micro-aggregates (<0.25mm) were highest in agro-forestry at both sites. Micro-aggregates had lower C as compared to macro-aggregates at both sites in all land use systems. Soil organic carbon (SOC) was more in forestry (5.00 g kg-1) in Takarla and at Mukerian, grassland possessed higher amount (15.88 g kg-1). Among the SOC fractions, the POC was most dominant but LC and HWC showed vulnerability to land use change. At Takarla, HWC (490 mg kg-1), LC (1626 mg kg-1), IC (7.00 mg kg-1), total POC (3389 mg kg-1) and mineralizable C (48.6 mg kg-1) were more in agro-forestry and mineralizable N ( 109.7 mg kg-1) was more in forestry. At Mukerian, HWC (1370 mg kg-1), LC (1963 mg kg-1), IC (5.75 mg kg-1), total POC (7991.6 mg kg-1) and mineralizable C (85.8 mg kg-1) were more in grassland and mineralizable N (116.7 mg kg-1) was more in forestry. Soil properties and physical, biological as well as functional pools of SOM are strongly influenced by different agricultural land-use. Carbon sequestration seems to be more in agro-forestry at Takarla and in grassland at Mukerian. Climatic conditions / temperature also influenced carbon fractions at both sites. At Mukerian, values for carbon fractions were high as compared to Takarla, due to comparatively low temperature which decreases the rate of decomposition of soil organic matter in Mukerian.enSoil ScienceThesis